1. Field of the Invention
The present invention relates to an electronic tide meter for calculating a spring tide day and displaying the calculated result, a spring tide day calculating method, and a recording medium which can be read by a computer recorded execute the method.
2. Description of the prior Art
The tides or the rising and falling of the sea level are of particular importance to fishermen. Above all, the spring tide day is the most important.
It is generally achieved by calculating the age or phase of the moon to acquire the tidal phenomena, especially the spring tide day. The calculated result of the moon age is available as the tidal information by the public agencies so that the spring tide day can be acquired by perusing the tidal information.
For those who always require the Information of the tidal phenomena, however, the perusal of the information is inefficient, and all the opened information on the tidal phenomena is not always required. Thus, there has been desired means for knowing the information of the desired tidal phenomena, especially the spring tide day.
Therefore, there has been proposed an electronic tide meter for displaying the calculated result of the spring tide day by deducing the moon age from a desired data (as will be called the "designated date") and by calculating the spring tide day to appear at first from the designated date, by using the deduced moon age.
According to the electronic tide meter disclosed in JP-B-6-25982, for example, the spring tide day is determined by calculating the moon age on the designated date at first and by calculating the number of days till the next spring tide appears, from the moon age while considering the period of the moon age.
Generally, the spring tide and the neap tide are individually defined as the states of tide at the full moon or the new moon and as the states of tide at the first and last quarters of the moon. However, the day deemed important for those in the fishing industry, is the day on which the tide level difference is at its maximum between the high and low tides in each particular geographical area. The spring tide day does not always coincide in this sense with the aforementioned one which is calculated depending exclusively on the moon age. This is because the tide level difference between the high and low tides is different depending on the geographical area, so that the spring tide day depending upon the area cannot be calculated exclusively from the moon age deduced from the calculation of the positions of the heavenly bodies.
In the electronic tide meter disclosed in JP-B-6-25982, the calculation is made by using only the moon age at the designated date. Even when the day actually having the maximum tide level difference is two days after the data calculated for a particular geographical area, there may occur such a large error that the actual spring tide day comes five days after the designated calculated date.
The invention has been conceived in view of those disadvantages belonging to the prior art and has an object to provide an electronic tide meter and a spring tide day calculating method for calculating a spring tide day corresponding to an area more accurately, and a recording medium which can be read by a computer stored with a program for causing the computer to execute the inventive calculating method.